from __future__ import annotations

from dataclasses import dataclass
import os
from pathlib import Path
import tempfile


def number(name: str, default: int, minimum: int = 1) -> int:
    try:
        value = int(os.getenv(name, str(default)))
    except ValueError as exc:
        raise ValueError(f"{name} must be an integer.") from exc
    if value < minimum:
        raise ValueError(f"{name} must be >= {minimum}.")
    return value


@dataclass(frozen=True)
class Settings:
    app_title: str = os.getenv("APP_TITLE", "Document Exam Trainer")
    embedding_model: str = os.getenv("EMBEDDING_MODEL_ID", "sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2")
    question_model: str = os.getenv("QUESTION_MODEL_ID", "Qwen/Qwen3-4B")
    grading_model: str = os.getenv("GRADING_MODEL_ID", "Qwen/Qwen3-14B")
    speech_model: str = os.getenv("SPEECH_MODEL_ID", "small")
    demo: bool = os.getenv("DEMO_MODE", "0") == "1"
    root: Path = Path(os.getenv("TRAINER_DATA_DIR", str(Path(tempfile.gettempdir()) / "document-exam-trainer-private"))).resolve()
    max_files: int = number("MAX_DOCUMENTS", 60)
    max_file_bytes: int = number("MAX_FILE_MB", 60) * 1024 * 1024
    max_total_bytes: int = number("MAX_CORPUS_MB", 160) * 1024 * 1024
    max_expanded_bytes: int = number("MAX_EXPANDED_MB", 240) * 1024 * 1024
    max_units: int = number("MAX_DOCUMENT_UNITS", 1200)
    max_chunks: int = number("MAX_CHUNKS", 2200)
    max_text_chars: int = number("MAX_TEXT_CHARS", 4_000_000)
    chunk_chars: int = number("CHUNK_CHARS", 1800)
    max_audio_seconds: int = number("MAX_AUDIO_SECONDS", 300)
    max_audio_bytes: int = number("MAX_AUDIO_MB", 60) * 1024 * 1024
    max_answer_chars: int = number("MAX_ANSWER_CHARS", 18000)
    session_ttl: int = number("SESSION_TTL_SECONDS", 7200)
    max_sessions: int = number("MAX_SESSIONS", 40)
    question_seconds: int = number("QUESTION_GPU_DURATION_SECONDS", 45)
    grading_seconds: int = number("GRADING_GPU_DURATION_SECONDS", 60)
    hint_seconds: int = number("HINT_GPU_DURATION_SECONDS", 25)
    max_prompt_tokens: int = number("MAX_PROMPT_TOKENS", 8500)


SETTINGS = Settings()